To produce high quality printed matter, it is essential that the printing press controllably and consistently deliver ink upon a web or other stock in the printing operation. A number of factors involved in the printing process directly influence the application of ink onto the web and thus affect the resulting appearance of the finished product. For example, such factors include (i) the composition, texture and finish of the web or other material to be printed, (ii) the color, composition and consistency of the ink being used, (iii) the type of ink fountain roll being used, and (iv) the nature of the printed image itself. For any particular set of operating conditions, there is an optimum ink film profile or thickness across the ink fountain roll which yields a printed image of desired quality.
To achieve a print image of desired quality, it is necessary to control the ink film profile or thickness at a plurality of locations along the ink fountain roll. A conventional printing press includes an ink fountain having a flexible metering blade in close proximity to an ink fountain roll. U.S. Pat. No. 4,008,664 discloses an ink fountain control apparatus for a printing press in which the spacing of a flexible blade from an associated fountain roll is adjustable at a plurality of locations along the fountain roll. In accordance with the U.S. Pat. No. 4,008,664, a plurality of rotatably adjustable keys are provided at spaced locations along the blade. The keys include means bearing against the blade to adjust the position of the blade relative to the associated fountain roll to thereby control the profile of the resulting ink film from the fountain.
Adjustment of fountain keys in previous known systems has been accomplished by manually turning a knurled head disposed on each key. U.S. Pat. No. 4,008,644 discloses a system in which each key is provided with a bidirectional motor operated manually to individually adjust each key from a remote location. Other known systems for adjusting fountain keys have included a travelling carriage with a relatively complex arrangement of clutches and gears which mesh with gear teeth disposed on the keys and selectively rotate a key a slight amount upon passing in one or the other direction.